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e-Article

On the Diversity and Coded Modulation Design of Fluid Antenna Systems
Document Type
Periodical
Source
IEEE Transactions on Wireless Communications IEEE Trans. Wireless Commun. Wireless Communications, IEEE Transactions on. 23(3):2082-2096 Mar, 2024
Subject
Communication, Networking and Broadcast Technologies
Computing and Processing
Signal Processing and Analysis
Diversity reception
Liquids
Modulation
Antennas
Power system reliability
Delays
Codes
Fluid antennas
outage probability
outdated channels
diversity
space-time rotations
coded modulation
iterative decoder
Language
ISSN
1536-1276
1558-2248
Abstract
Reconfigurability is a desired characteristic of future communication networks. From a transceiver’s standpoint, this can be materialized through the implementation of fluid antennas (FAs). An FA consists of a dielectric holder, in which a radiating liquid moves between pre-defined locations (called ports) that serve as the transceiver’s antennas. Due to the nature of liquids, FAs can practically take any size and shape, making them both flexible and reconfigurable. In this paper, we deal with the outage probability of FAs under general fading channels, where a port is scheduled based on selection combining. An analytical framework is provided for the performance with and without errors due to post-scheduling delays. We show that although FAs achieve maximum diversity, this cannot be realized in the presence of delays. Hence, a linear prediction scheme is proposed that overcomes delays and restores the lost diversity by predicting the next scheduled port. Moreover, we design space-time coded modulations that exploit the FA’s sequential operation with space-time rotations and code diversity. The derived expressions for the pairwise error probability and average word error rate give an accurate estimate of the performance. We illustrate that the proposed design attains maximum diversity, while keeping a low-complexity receiver, thereby confirming the feasibility of FAs.